Hospital beds and other occupant supports include a frame and a mattress or other occupant interface. An occupant confined to the bed for an extended time may develop pressure ulcers, especially at the locations on the occupant's body that exert the most pressure on the occupant interface. The risk of an occupant developing pressure ulcers can be reduced by controlling the microclimate, i.e. parameters such as temperature in the immediate vicinity of the occupant. In particular, the risk of pressure ulcers can be reduced by cooling the susceptible portions of the occupant's body.
One way to control the microclimate involves the use of a “topper”, an envelope of material that rests on the mattress so that the topper, rather than the mattress itself, serves as the occupant interface. The topper has a fluid inlet and a fluid outlet. In operation, a blower forces a fluid, usually ambient air, into the interior of the topper by way of the inlet. The air enters the topper and discharges to the environment through the outlet. The flow of ambient air through the topper helps convect heat away from the parts of the occupant's body in contact with the topper, and thereby reduces the risk of pressure ulcers. Heat convection can be enhanced by using chilled air rather than ambient air.
Although microclimate management toppers as described above are effective they are not without limitations. The heat withdrawal capacity of the described topper is substantially spatially uniform, i.e. it's potential for extracting heat from those portions of the occupant's body that bear heavily on the occupant interface is the same as its potential for extracting heat from those portions of the occupant's body that bear lightly on the interface (and which therefore don't require as much heat extraction). The uniformity of heat extraction potential even extends to those portions of the topper not in contact with the occupant. In addition, the fact that a large portion of the occupant's body contacts the topper means that the benefits of using chilled air can be offset by the associated risk of hypothermia. Although the risk of hypothermia might be addressed by compartmentalizing the topper and directing air only to selected compartments or zones, such an approach complicates the architecture of the topper and requires ductwork and valves that increase the weight, cost and complexity of the bed and adversely affect bed transportabilty, marketability and reliability.
What is needed is an occupant support having localizable microclimate management capabilities while avoiding at least some of the disadvantages described above.